Wildlife of the Week!

Who is looking forward to another Wildlife of the Week? We know we are! This week we are delighted to highlight another incredible species. You may have noticed that many of our recent features have focused on seabirds; there is such a high diversity and a critical importance of seabirds in the Salish Sea. The species we will discuss today is often recognized by its distinct orange bill and shoreline foraging. To read on about the Black Oystercatcher, read on below!

The Black Oystercatcher is a familiar bird to those who frequent the West Coast. This Oystercatcher is a large-sized bird with a long, pointed bill and a dark body of black and brown. A reasonable size comparison is the crow, as the Oystercatcher measures between 42-47 cm long and 500-700g. The bill is typically bright orange and is a telltale identifier for the species. Other features include a yellow eye and pink legs.

Juveniles and adults further south may vary slightly in color patterns, the latter being linked to hybridization with another species. The bird has smooth, uniform plumage and is a remarkable sight when flying, perching or foraging along the shoreline. 

The seabird’s range is large, stretching along much of the West Coast, from Alaska down to Baja California (though more sparse at the latter range). You might spot a Black Oystercatcher around rocky shorelines, jetties, islands, headlands, tide-pools and beaches, appearing to prefer rocky areas over sandy ones (look for them especially on mussel beds). This species has even been seen around open tidal mudflats and grassy areas.

The Black Oystercatcher appears to seek out low or falling tides, as this aids them in discovering prey quickly as the water recedes. During high-tide, the birds appear to rest and perch in large groups, often preening their feathers. The bird tends to remain in a range year-round, and only some numbers of individuals move seasonally. 

The name of this seabird certainly gives way to their dietary habits, but you may not know their unique way of obtaining and consuming prey! As well, the Black Oystercatcher could have been named less specifically, as they have been recorded to rarely feed on oysters, but more often other invertebrates instead. The Black Oystercatcher utilizes a few methods to break into the tough shells of bivalves (creatures with two shells, such as a mussel). One, the bird will use their sharp beak to access a slightly ajar shell, cutting off the invertebrate’s muscles and taking the animal from inside. They may also access these muscles at the hinge area. Two, the bird might use force to smash the shell apart, exposing its contents.

Though it is true this Oystercatcher will feed on creatures such as clams, mussels and oysters, they will also prey on other shelled and non-shelled animals such as chitons and limpets, worms, crabs and other crustaceans, urchins or washed up jellyfish, anemones, or herring spawn. Interestingly enough, they can even use clues on the sand to discover buried organisms. 

The Black Oystercatcher nests on the ground with its partner, the two remaining together for the duration of the year. Nests are built by both partners above the high-tide line and on the ground along rocky shorelines, headlands or beaches and commonly on islands. The nest may be placed on a grassy, gravelly, shelly, sandy or sunken-in area of the beach. The birds will selectively choose their nest site so that it has adequate access to shore, the shoreline in front of their nest being their primary hunting and territory zone. They will avoid nesting on cliffs.

Cooperative incubating, rearing and feeding is done, with clutch sizes range between 1-4 eggs. Once hatched, the young birds will learn life techniques, fly at about 5 weeks and become independent within a few months. After the breeding and rearing season, pairs may choose more productive feeding areas where large congregations may gather, or may remain in the current range. 

The Black Oystercatcher may be seen in groups of dozens to hundreds, but as mentioned, tends to be quite territorial during breeding season. The bird is vulnerable to rats and foxes which have been introduced into areas around Alaska. The Black Oystercatcher is also incredibly sensitive to oil spills, human beach disturbance and other human induced habitat issues (e.g. heat waves, habitat destruction). This seabird is still relatively common along the Pacific Coast, but attention has been put towards their vulnerability. 

If you would like to test your knowledge on this magnificent seabird, try out some trivia below!

1. True or False? A male bird may carve out several netting sites, but the female ultimately chooses one. (ANS: TRUE). 
2. How long is egg incubation? (ANS: 24-29 days). 
3. The Black Oystercatcher is referred to as a(n) ________ hunter (auditory, visual, cooperative). (ANS: Visual). 

BONUS CHALLENGE: 

The oldest Black Oystercatcher was over x years old? 

6 years and 2 months. 

Article By: Alexa D./Five Star Whale Watching

To learn more, check out our References below!

1. “Black Oystercatcher.” All About Birds. The Cornell Lab. Cornell University. https://www.allaboutbirds.org/guide/Black_Oystercatcher/overview. 
2. “Black Oystercatcher.” Guide to North American Birds. National Audubon Society. https://www.audubon.org/field-guide/bird/black-oystercatcher.